Technical Field
The present invention relates to a liquid discharge head that discharges a liquid and to a liquid discharge apparatus that includes the liquid discharge head.
Related Art
A liquid discharge apparatus (e.g., an ink jet printer) includes a liquid discharge head that discharges a liquid by using piezoelectric elements. Such a liquid discharge head includes a piezoelectric element-formed substrate in which piezoelectric elements are formed in a stacked state in a plate member that constitutes a portion of pressure chambers provided in liquid flow paths that communicate with nozzles, and discharges the liquid from the nozzles by outputting drive signals to the piezoelectric elements formed in the piezoelectric element-formed substrate.
Examples of such liquid discharge heads include a liquid discharge head having a structure in which a drive IC that outputs drive signals input to the liquid discharge head based on control signals also input to the liquid discharge head is packaged directly on a piezoelectric element-formed substrate so as to reduce the size of the liquid discharge head. Japanese Patent Application Publication No. 2014-51008, for example, describes a liquid discharge head in which a drive IC (driver IC) is directly packaged on a piezoelectric element-formed substrate (vibration plate) by connecting a plurality of bumps provided on the piezoelectric elements formed in the piezoelectric element-formed substrate to connection terminals provided on the piezoelectric element-formed substrate in a state in which the drive IC covers the piezoelectric elements.
However, in the related-art liquid discharge head, wires (electric wiring) through which drive signals and control signals are transmitted are connected directly to the drive IC. Therefore, for example, in the case where the number of nozzles increases for a higher nozzle density, the number of wires that transmit necessary signals to the drive IC accordingly increases, so that the impedance of the wires with regard to the drive signals and the control signals increases. In this case, there is a problem that signals transmitted through wires may have distortion due to an increase of impedance, causing fluctuations in liquid discharge characteristics. Therefore, it is desired to reduce the impedance of the wires in the liquid discharge head.
Such a problem is substantially common to liquid discharge heads that receive input of drive signals to drive the piezoelectric elements and control signals to control the output of the drive signals to the piezoelectric elements and that discharge liquid as the piezoelectric elements are driven by the output drive signals and also to the liquid discharge apparatuses equipped with such liquid discharge heads.